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  <title>查找字符串首次出现的位置</title>

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</div><hr /><div id="function.strpos" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">strpos</h1>
  <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">strpos</span> &mdash; <span class="dc-title">查找字符串首次出现的位置</span></p>

 </div>
 
 <div class="refsect1 description" id="refsect1-function.strpos-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="type">int</span> <span class="methodname"><strong>strpos</strong></span>
    ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$haystack</code></span>
   , <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$needle</code></span>
   [, <span class="methodparam"><span class="type">int</span> <code class="parameter">$offset</code><span class="initializer"> = 0</span></span>
  ] )</div>

  <p class="para rdfs-comment">
   返回 <em><code class="parameter">needle</code></em> 在 <em><code class="parameter">haystack</code></em> 中首次出现的数字位置。与 <span class="function"><a href="function.strrpos.html" class="function">strrpos()</a></span> 不同，在 PHP 5 之前，该函数可以使用一个完整字符串作为 <em><code class="parameter">needle</code></em>，并且整个字符串都将被使用。
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.strpos-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<em><code class="parameter">haystack</code></em></dt>

     <dd>

      <p class="para">
       在该字符串中进行查找。
      </p>
     </dd>

    
    
     <dt>
<em><code class="parameter">needle</code></em></dt>

     <dd>

      <p class="para">
       如果 <em><code class="parameter">needle</code></em> 不是一个字符串，那么它将被转换为整型并被视为字符的顺序值。
      </p>
     </dd>

    
    
     <dt>
<em><code class="parameter">offset</code></em></dt>

     <dd>

      <p class="para">
       可选的 <em><code class="parameter">offset</code></em> 参数可以用来指定从 <em><code class="parameter">haystack</code></em> 中的哪一个字符开始查找。返回的数字位置是相对于 <em><code class="parameter">haystack</code></em> 的起始位置而言的。
      </p>
     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.strpos-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   以整型返回位置信息。如果没找到 <em><code class="parameter">needle</code></em>，<span class="function"><strong>strpos()</strong></span> 将返回<span class="type"><span class="type 布尔型">布尔型</span></span>的 <strong><code>FALSE</code></strong> 值。
  </p>
  <div class="warning"><strong class="warning">Warning</strong><p class="simpara">此函数可能返回布尔值
<strong><code>FALSE</code></strong>，但也可能返回等同于 <strong><code>FALSE</code></strong> 的非布尔值。请阅读 <a href="language.types.boolean.html" class="link">布尔类型</a>章节以获取更多信息。应使用
<a href="language.operators.comparison.html" class="link">===
运算符</a>来测试此函数的返回值。</p></div>
 </div>


 <div class="refsect1 examples" id="refsect1-function.strpos-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-4797">
    <p><strong>Example #1 使用 <em>===</em></strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />$mystring&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'abc'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$findme&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'a'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$pos&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">strpos</span><span style="color: #007700">(</span><span style="color: #0000BB">$mystring</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$findme</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">//&nbsp;注意这里使用的是&nbsp;===。简单的&nbsp;==&nbsp;不能像我们期待的那样工作，<br />//&nbsp;因为&nbsp;'a'&nbsp;是第&nbsp;0&nbsp;位置上的（第一个）字符。<br /></span><span style="color: #007700">if&nbsp;(</span><span style="color: #0000BB">$pos&nbsp;</span><span style="color: #007700">===&nbsp;</span><span style="color: #0000BB">false</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">"The&nbsp;string&nbsp;'</span><span style="color: #0000BB">$findme</span><span style="color: #DD0000">'&nbsp;was&nbsp;not&nbsp;found&nbsp;in&nbsp;the&nbsp;string&nbsp;'</span><span style="color: #0000BB">$mystring</span><span style="color: #DD0000">'"</span><span style="color: #007700">;<br />}&nbsp;else&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">"The&nbsp;string&nbsp;'</span><span style="color: #0000BB">$findme</span><span style="color: #DD0000">'&nbsp;was&nbsp;found&nbsp;in&nbsp;the&nbsp;string&nbsp;'</span><span style="color: #0000BB">$mystring</span><span style="color: #DD0000">'"</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">"&nbsp;and&nbsp;exists&nbsp;at&nbsp;position&nbsp;</span><span style="color: #0000BB">$pos</span><span style="color: #DD0000">"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

   </div>

   <div class="example" id="example-4798">
    <p><strong>Example #2 使用 !==</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />$mystring&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'abc'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$findme&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'a'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$pos&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">strpos</span><span style="color: #007700">(</span><span style="color: #0000BB">$mystring</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$findme</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">//&nbsp;使用&nbsp;!==&nbsp;操作符。使用&nbsp;!=&nbsp;不能像我们期待的那样工作，<br />//&nbsp;因为&nbsp;'a'&nbsp;的位置是&nbsp;0。语句&nbsp;(0&nbsp;!=&nbsp;false)&nbsp;的结果是&nbsp;false。<br /></span><span style="color: #007700">if&nbsp;(</span><span style="color: #0000BB">$pos&nbsp;</span><span style="color: #007700">!==&nbsp;</span><span style="color: #0000BB">false</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">"The&nbsp;string&nbsp;'</span><span style="color: #0000BB">$findme</span><span style="color: #DD0000">'&nbsp;was&nbsp;found&nbsp;in&nbsp;the&nbsp;string&nbsp;'</span><span style="color: #0000BB">$mystring</span><span style="color: #DD0000">'"</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">"&nbsp;and&nbsp;exists&nbsp;at&nbsp;position&nbsp;</span><span style="color: #0000BB">$pos</span><span style="color: #DD0000">"</span><span style="color: #007700">;<br />}&nbsp;else&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">"The&nbsp;string&nbsp;'</span><span style="color: #0000BB">$findme</span><span style="color: #DD0000">'&nbsp;was&nbsp;not&nbsp;found&nbsp;in&nbsp;the&nbsp;string&nbsp;'</span><span style="color: #0000BB">$mystring</span><span style="color: #DD0000">'"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

   </div>

   <div class="example" id="example-4799">
    <p><strong>Example #3 使用位置偏移量</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #FF8000">//&nbsp;忽视位置偏移量之前的字符进行查找<br /></span><span style="color: #0000BB">$newstring&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'abcdef&nbsp;abcdef'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$pos&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">strpos</span><span style="color: #007700">(</span><span style="color: #0000BB">$newstring</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'a'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">);&nbsp;</span><span style="color: #FF8000">//&nbsp;$pos&nbsp;=&nbsp;7,&nbsp;不是&nbsp;0<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

   </div>
  </p>
 </div>


 <div class="refsect1 notes" id="refsect1-function.strpos-notes">
  <h3 class="title">注释</h3>
  <blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">此函数可安全用于二进制对象。</span></p></blockquote>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.strpos-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="function.strrpos.html" class="function" rel="rdfs-seeAlso">strrpos()</a> - 计算指定字符串在目标字符串中最后一次出现的位置</span></li>
    <li class="member"><span class="function"><a href="function.stripos.html" class="function" rel="rdfs-seeAlso">stripos()</a> - 查找字符串首次出现的位置（不区分大小写）</span></li>
    <li class="member"><span class="function"><a href="function.strripos.html" class="function" rel="rdfs-seeAlso">strripos()</a> - 计算指定字符串在目标字符串中最后一次出现的位置（不区分大小写）</span></li>
    <li class="member"><span class="function"><a href="function.strrchr.html" class="function" rel="rdfs-seeAlso">strrchr()</a> - 查找指定字符在字符串中的最后一次出现</span></li>
    <li class="member"><span class="function"><a href="function.substr.html" class="function" rel="rdfs-seeAlso">substr()</a> - 返回字符串的子串</span></li>
    <li class="member"><span class="function"><a href="function.stristr.html" class="function" rel="rdfs-seeAlso">stristr()</a> - strstr 函数的忽略大小写版本</span></li>
    <li class="member"><span class="function"><a href="function.strstr.html" class="function" rel="rdfs-seeAlso">strstr()</a> - 查找字符串的首次出现</span></li>
   </ul>
  </p>
 </div>


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